1. Technical Field
The present disclosure relates to a gate drive circuit to drive a semiconductor switch.
2. Description of the Related Art
As of recent, increased interest in the environment has led to demand for electric power conservation in all sorts of electric devices. Inverter systems, which switch electric power, are being viewed as being a major point in producing electric devices with reduced electric power consumption. Inverters are in use in a wide range of electric devices, such as everyday electric devices such as air conditioners, washing machines, and refrigerators, industrial-use electric devices such as power conditioners installed in solar cells, and electric device onboard electric automobiles and the like.
Such inverters are configured including a semiconductor switch for switching electric power, and a gate drive circuit for driving the semiconductor switch. A semiconductor switch, which is a power device, typically operates under high voltage of several tens of volts to several thousand volts.
On the other hand, a control signal for turning a semiconductor switch on/off is supplied from a control circuit (control integrated circuit (IC)) which operates at several volts or less. Accordingly, in such a case the gate drive circuit supplies a drive signal to the semiconductor switch while ensuring electrical isolation between an output side where the semiconductor switch is provided and an input side where the control circuit is provided. A gate drive circuit using an electromagnetic resonance coupler has been proposed of such a gate drive circuit (e.g., see S. Nagai et al., “A DC-Isolated Gate Drive IC with Drive-by-Microwave Technology for Power Switching Devices”, 2012 IEEE ISSCC Digest of Technical Papers, Vol. 65, pp. 404-405, Feb. 2012, hereinafter referred to as “Nagai”).
There is demand for a gate drive circuit which instantaneously supplies a great current to the gate terminal of a semiconductor switch, to turn the semiconductor switch on at a high speed.